Electrothermal switch.



No. 851,410. EATENTED APRa 23, 1907. J. ERICKSON.

ELBGTROTHERMAL SWITCH.

APPLICATION FILED 00T.21,1904.

lI/zae y@ g Inge/M022' Q? (www, Wm QZ Mfmw JOHN ERICKSON, or OHIOAGOILEINOIS, fissIeNon To AUTOMATIC ELECTRIC CMPANY, OF CHIOAGG, ILLINOIS.

ELEGTROTHERML SWlTCl-l.

iva-851,410.

Specification of Letters Patent.

Patented April 23, 1907.

Application filed October Z1, 1904. Serial No. 229,389.

To @ZZ whom it may cm2/cern:

Be it known that I, JOHN ERICKSON, a citizen of the United States of America, and a resident of Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Electrothermal Switches, of which the following is a specification.

My invention contemplates an improved and highly etlicient form of electro-thermallyoperated switch adapted more particularly for use in circuits where it is desirable to protect delicate apparatus or electrical devices, such, for example, as telephonie and other like apparatus, against the injurious eifects of abnormally strong electrical currents.

In an electro-thermal switch embodying the principles of my invention, provision is made for maintaining the continuity of an electrical circuit, one of the elements for so doing consisting of a resistance of such character that heat will be generated as soon as the current becomes abnormally strong, or as soon asa trespassing current shows its presence in the circuit. The continuity of the circuit is also maintained by certain metallic I parts lvhich are normally held in contact with each other by means ofa suitable quantity of solder or other heat-responsive material, but which parts are not soldered together. In order that the switch may respond readily to abnormally strong currents, so as to open the circuit before the abnormal flow o'f current can injure any of the apparatus or instruments to which protection is afforded by the switch, the said resistance and solder or other fusible material are associated closely together. In this way, the circuit is opened by the separation of the metallic parts as soon as sufficient heat is generated by the resistance to soften the solder or other heat-responsive material; and provision is also preferably made whereby the outer or line portion of the circuit is at the same time connected with a conductor leading to ground, whereby the abnormally strong or trespassing current is not only excluded from the apparatus or instruments to be protected,'but is also afforded a path of escape to ground.

lith the preferred construction, the switch-contacts which `are held together through the medium of the solder are separated as soon as the latter softens; but the which the solder is directly applied do not separate when the switch is operated by an Consequently, the solder y then be closed or restored to their normal condition without the necessity of removing any of the parts, and 'without even the necessity of supplying new solder' or other fusible material. rI`hus, after the switch has been operated by abnormal current, it is only necessary to close the contacts for maintaining the continuity of the circuit; and while this self-soldering feature of my improved electro-thermalswitch is an important one, it Will be seen that the device as a whole embodies various other features which are novel and advantageous.

One ofthe important features of my invention Lconsists in employing two metallic parts which are normally soldered together, but adapted to move relatively to each other when the solder is melted or softened, and which are adapted to, at all times, exclude the air from the solder, thereby preventing the solder from oxidizing each time it is melted orsoftened, and thus making it possible to operate the switch hundreds of times without any appreciable loss or deterioration of the solder.

In the accompanying drawings, Figure l is a face view of an electro-thermal switch einbodying the principles of my invention, a portion of the mounting for the switchsprings being shown in section; Fig. 2 is a side elevation of thedevice shown .in Eig. l; rig. 3 is a perspective view of the electrothermal or heat-responsive portion of the said device; Figs. L and 5 are detail views showing the switch-contacts in different positions; Fig. 6 is a section on line 6-5 of Fig. 5.

As thus illustrated, the body A of the switch is preferably and advantageously composed of a sheet-metal stamping provided at one end with the ears or lugs o, and at the other end with a flat portion a1. The switch-springs B, C and D, having terminal portions d, l) and c, and with the interposed strips of insulation E, are' secured to the portion a1 bv means of screws c and a CiampinoP .f i n plate el. At this end of the structure, the

parts which are soldered together and tol said body A may also bc provided with IOO IOS

screw-holes a2, whereby the device as a whole may be secured to a suitable support. At its other end, the said body A is provided with a threaded opening a3 adapted to receive the threaded end portion of a short screw F. rlhe said screw serves as a pivot for the swinging; support or block of insulation'G, which latter is adapted to have a limited swinging movement between the stops et. A threaded openingg is provided at the free end portion of the said block or' insulation, said threaded opening being' adapted to receive the threaded end portion of a metallic post g1.

l shown, the said post is provided with a flange or shoulder portion g2, and also witha sep arately formed collar or encircling ring g3. the

p latter being secured to the flange or shoulder g2 by means olu the solder or other suitable heat-responsive material gt. A coil-spring g5 is interposed between the opposing surfaces of ythe block of insulation G and -the hat encircling ring` g3. .The coil or other suitable resistance g is wrapped around the outer reduced end portion ol the metal post g1, and is covered by a cap of insulation 97. lt will 'be observed that the ring` g3 has its edge or periphery provided with ratchet teeth, as shown more clearly in lligs. l, 5, and \5. Normally, the end oi the line spring` C engages a tooth ,on the ring` g3, as shown in Figs. l and 5; and the spring B, which may be a switchboard-spring, is connected with the coil gG by means of a conductor it will be understood that the other end of the coil ce is secured in a suitable manner to the metallic post g1, whereby the spring C, the vtoothed ring; g3, the coil or resistance g, and the springl are all normally connected in series in the circuit including the' apparatus or instrument to be protected. lt will be seen that the parts are so relatively disposed, and that the notches olf the ring g3 are such, that the tension of the .spring C 'tends normally to hold the block oi insulation G against one oi" the stops a.

Sup-pose nowthat abnormal current, such as what is commonly known as a sneak current, or some other trespassing current, should show vits presence in the line circuit. ln such case, the abnormal condition of the current-flow in the circuit causes the coil or other resistance g to generate considerable heat, to thereby soften or melt the solder g4. rthis, ol course, by reasonei' the character et the said resistance, happens before the current can do any harm to the .apparatus or ine strumentsxto be protected, and results in a release ot the toothed ring; g3. when thus released, allows the spring` C to escape from engagement with the tooth on the ring, and thus opens the conducting path which is normally maintained in a closed or continuous condition by the contact between the said springr and toothed ring. At this juncture, it will be seen that the coil-spring y rThe said ring,

. stimo keeps the toothed ring g3 pressed tightl against the flange or shoulder g2; and suc being the case, the solder g4 then instantly cools or hardens and thereby resolders the said toothed ring, and flange together. ln other words, the solder, when softened or melted, simply allows the toothed ringT to rotate upon the metal post g1, so as to break the continuity of the conducting path, and then instantly cools or hardens and restores the toothed ring of the said post to its normal or rigidcondition. After this, the block of insulation G can then be swung over toward the outer stop 0 so as to permit the spring C to be bent or sprung into its normal condition, and, the block of insulation G then swung back toward the other stop. and in such manner as to cause the toothed ringto re-engage the end of the said spring. way,it is evident that the electro-thermal switch is of a self-soldering character-that is to say, it resolders the parts together as soon as the circuit or conducting path is opened; and it 1s then only necessary to bring the normally-closed switch-contacts into re# engagement with each other in order to rcstore the switch to its normal condition. is shown, the spring; C, when released, engages the spring D; and the said spring D 4can have its terminal connected with the ground con` ductor, so as to afford a path of escape tor the trespassing current.

he sell-soldering vfeature ol my improved electro-thermal switch is an important one, 'as it obviously makes it unnecessary to in any way repair the switch after it has been operated by an abnormal current-flow. lt is evident, howeventhat, with the improved construction and arrangement shown, the norinally-closed conducting path can be easily opened, for any purpose, without removing or detaching any of the dill'erent parts. rlhe arrangement ci" the switchsprings in a group at one end or the body constitutes a i'urther feature ci' improvement. ln addition, l aim to provide a construction oi' such character that, in its entirety, the switch is not only reliable and erh cient in use, but also simple and economical to manufacture; and also aim to provide a device that is comparatively easy and inexpensive to install and maintain in condition tor use.

lt is a matter of common knowledge that solder, when exposed to the atmospherelin a melted condition, will be subject to oxidation; but with my improved construction, involving two metallic parts which are maintained tightly in contact with each other, with only a very thin iilin ol solder between them, and which, even when the solder melts, are adapted to rotate or move relatively to each other without exposingr the solder to the atmospl'ierc, it is evident that no such oxidizenetion can occur; and Afor this reason, s

ln this lOO . electro-thermal switch embodying this broad Aemployed as the means for attaching the switch to circuit Wire, and for including the devices in a circuit or circuits-either normally closed or open-or for making othe necessary or desired connections.

The toothed ring g3 is,it willbe seen, adapted to serve as a rotary detent. Under the influence of the spring g5, and with the relative arrangement shown, this 'detent is adapted to automatically resume an operative condition upon the cessation of abnormal current conditions in the device of which it is a desirable feature. lt is essential, ot course,

-thatthe parts which are normally soldered together be not only capable of resoldering themselves together upon the cessation ci abnormal current` conditions, but that they also be capable ot re-soldering themselves together in an operative condition-that is, the condition or relation oi the parts to each other, after the solder' cools, must be an operative'one, and one which leaves the excess current-operated device in condition tor use. The switch as a whole, of course, will not automatically restore itself, inasmuch as itis necessary` to manually re-set the switchspring C-that is, to manually bend the end oi this spring into engagement With the rotary detent. The excess current-operated device is, however, of a sell-restoring nature, inasmuch as the mere cooling or re-harden ing of the solder leaves this device, as stated, in condition tor immediate use. ln other Words, ,the relation of the soldered parts to each other, after the solder has cooledor rehardened, is an operative one and ci such character as to leave the excess current-op erateddevice in condition to be s inply reapplied to the switch-that is, to the switch-I springs or other circuit-controlling contacts.

What l claim as my invention is:

1. An electro-thermal' switch comprising a body composed ci a sheet-metal stamping a group of switch-springs and interposed strips of insulation suitably secured to a portion of said body, a block of insulation pivotally mounted at the other end of said body, a metal post mounted in the free r swinging end portion ofsaid block of insulation, a toothed ring encircling said post and normally soldered thereto, resistance coil mounted on said post and-,associated with said solder, said post having` a shoulder to which the said toothed ring is soldered, suitable means-'forconnecting the said resistanco, toothed Aring and one oi said springs in series, said spring normally engaging a tooth on said ring, and spring means for keeping the said toothed ringpressed tightly against said shoulder When the solder' melts as a result of the-heat generated by said resistance, and whereby the toothed ring and spring are separated by the melting of the solder 'and the toothed ring and metal pcstthen auto-4 matically re-soldered together upon the cessation of current throughthe resistance and the consequent cooling or hardening of' the solder.

2. An electro-thermal switch comprising means for preserving the normal condition of a conducting path, said means including a metal post provided with a shoulder, a toothed ring encircling said post and adapted to rotate thereon, the ring and shoulder, however, being normally soldered together, a suitable heat generating resistance associatedvvith said solder, a spring tending at all times to torce the said ring against the said shoulder, and a switch-spring normally' engagmg a tooth of said ring.

An electro-thermal switch comprising a seit-soldering heat-coil device, together with suitable switch contacts operated by said heat-coil device, said heat-coil bein adapted to be operated by abnormal current conditions, and to automatically resume an opera tive condition upon the cessation of abnormal current conditions therein, t e said svntch having a plurality ot axes ol' move-l ment, one axis adapted to swing about the other t'o Jacilitate resetting ot the structure as a Whole, substantially as described.

'An electro-thermal switch comprising a .body composed of a sheet-inetal stamping, a

group ci switch-springs interposed strips ot insulation suitably secured to a portion of said body, a block of insulation pivotally mounted at the otherend ot said body, a metal post mounted in the tree or swinging end portion ot said block ci insulation, a toothed ring encircling said post and normally soldered thereto, a resistance coil `meunted on said post and associated with said solder, said' post having a shoulder' to 'which the said toothed ring is soldered, suitable means for connecting the said resistance, toothed ring and one of said springs in series,

said spring normally engaging a' tooth on said ring, and spring means tor lieeoing the said toothed ring pressed tightly Aist said shoulder when the solder melts as result ot the heat generated by said resistance, and whereby the toothed ring and spring are separated by the inciting of the solder and the toothed ring and metal post then autolinatically re-soldered together upon the cese sation ot current through the resistance and the consequent cooling or hardening of the solder, together with means for connecting the said switch with or in one` or more circuits or circuit connections.

5. An electro-thermal. switch comprising yico IlO

means ,for preserving the normal condition of a conducting path, said means including a metal post provided with a shoulder, a toothed ring encircling said post and adapted to vrotate thereon, the ring and shoulder,

however, being normally soldered together, a suitable heatgenerating resistance .associated 'with' said solder, a spring tending at all timesto force the said ring against the said shoulder, and a switch-spring normally engaging, a tooth of said ring, together with means for connecting the said switch with or in one or more circuits'or circuit connections.

6. An electro-thermal switch comprising a self-soldering heat-coil device, said heat-coil device being adapted to be operated by abnorf zio mal current conditionabut'adapted also to automatically resume an operative condition upon the cessation of abnormal current conditions therein, together -with means for connecting the said switch in one'or more circuits or circuit connections, the said switch c having a plurality of axes of movement, one

whole.

8. ln apparatus of the class specified, the combination of a heat producing means, a rotary detent normally held against rotation by a heat susceptible material, circuit controlling means adapted to produce a relative turning between the heat producing` means and the rot ary detent, when the heat suscepn tible material is softened, a spring g5 held under permanent tension to ensure self return oit the parts to operative condition preparatory to manual restoration to normal condition of the structure as a whole, said rotary detent engaged by the spring g5, for the purpose set forth.

' 9. lin an electrical circuit protector, the combination of a heat concentrating device, a 'wheel having a plurality of teeth, a solder joint normally holding said wheel against movement, a strip spring adapted to engage the teeth'of said wheel, whereby upon the passage of an 'unduly strong current in the device, the heat concentrating device softens the solder and permits the wheel to be turned to release the spring andresets the wheel in lposition to reengage the spring, the wheel asia-io under permanent tension to ensure self return of the parts to operative condition preparatoryto manual restoration tonormal condition of the structure as a whole, said wheel, engaged on its under side by said spring g5, for the purpose set forth.

10. ln an electrical controller comprising thermally operable securing means releasable lon a change in electrical circuit conditions,

having provisions whereby it is automatically resecured in operable condition prepara tory to another operation, a pivoted arm G upon the distal end of which are mounted parts capable of self return to operative condition preparatory to manual restoration to normal condition of the structure as a whole.

11. in apparatus of the class specified, the combination of a heat producing means, a rotary detent normally held against rotation by aheat susceptible material, circuit controlling means adapted to produce a relative turning between the heat producing means and the rotary detent, when the heat susceptible material is softened, a pivoted arm G upon the distal end ot which are mounted the parts capable of self return to operative. conditionpreparatory to manual restoration to normal condition of 'the structure as a whole, and means for limiting the swing oi" said arm.

12. in an electrical circuit protector, the combination of a heat concentrating device, a wheel having a plurality of teeth, a solder -joint normally holding said wheel against movement, a strip spring adapted to engage v the teeth of said wheel, whereby upon the passage of an unduly strong current 1n the device, the heat concentrating device softens the solder and permits-the wheel to be turned to release the spring and resets the wheel in position to re-engage the spring, the wheel being automatically resoldered after operation in such reset position, a pivoted arm G upon the distal end of which are mounted the parts capable of self return to operative condition preparatory to manual restoration to i normal condition of the structure as a whole,

and a plate Aupon which all said parts are mounted.

13. ln an electrical controller comprising thermally operable securing means releasable on a change in electrical circuit conditions, having provisions whereby it is automatically resecured in operable condition preparatory for another operation, the pivot F, the arm G mounted on said pivot, and the spring g5 carried by the distal end of said arm, ada pted to ensure self return of the parts to opera-. tive conditipn preparatory to manual restoration to normal condition of the struct-ure as a wholel' i 14C. ln apparatus of the class specified, the combination of a heat producing meansfa rotary detent normally .held against rotation by a heat susceptible material, circuit coniog,

trolling means ada ted to pr'oduce a relative turning between the heat producing means and the rotary detent, when the heat susceptible material is softened, the ivot F, the arm G mounted on said pivot, t e spring g5 carried by the distal end of said arm, adapted to ensure self return of the parts to operative condition preparatory to manual restoration to normal condition of the structure as a whole, said rotary detent enga ed by said spring g5, for the purpose set fortlgi.

15. In an electrical circuit protector, the combination of a heat concentrating device, a Wheel having a plurality of teeth, a solder joint normally holding said Wheel against movement, a strip s ring adapted to engage the teeth of said Wiieel, whereby upon the passage of an unduly strong current in the device, the heat concentrating device softens the solder and permits the Wheel to be turned to release the spring and resets the Wheel in osition to re-engage the spring, the Wheel eing automatically resoldered after opera-. tion in such reset position, the pivot F, thel arm G mounted on said pivot, the spring g5 carried by the distal end of said arm, adapted to ensure self return of the parts to operative condition reparatory to manual restoration to normalp condition of the structure as a Whole, said Wheel en aged on its under side by said spring g5, for t e purpose set forth.

16. In a device of the class specified, the combination of a toothed metal Wheel, a

metal support for said Wheel, solder between said support and Wheel, a heat generating resistance associated With'said solder, spring means for keeping the Wheel and support ressed tightly together to exclude the air om said solder, and means for engaging the teeth of said Wheel to eXert spring pressure thereon and close circuit through said resistance.

17. A device of the class specified, comprising self-soldering i'means provided with a dplurality of axes of movement, one arms a apted to sWin about the other to facihtate resetting o said device, and suitable parts movable about said axes.

18. A self-soldering electro-thermal switch comprising-a bodily movable toothed wheel, solder for normally holding the Wheel against rotation, a spring engaging a tooth of said Wheel, adapted to engage any other tooth should the Wheel be rotated, a suitable resistance associated with said solder, a circuit for passing electric current through said resistance, and means for effecting the bodily movement of the toothed Wheel, said solder adapted to be fused by heat generated by said resistance.

Signed by me at Chicago Ill this 12th day of Oct 1904.

JOHN ERICKSON. Witnesses:

CLARENCE M. THORNE, JENNIE Nomar 

